Diathermy dosage meter



Nov. 4, 1941.

All "an C. K. GIERINGER DIATHERMY DOSAGE METER Filed Jan. 12, 1937 INVENTOR.

Patented Nov. 4, 1941 Carl K. Gieringer, Miamito'wn, Ohio,

The Liebel-Flarsheim Company, Ohio, a corporation of Ohio assignor to Cincinnati,

Application January 12, 1937, Serial No. 120,261

3 Claims.

This invention relates to electro-therapeutics. More particularly, the invention is directed to improvements in the measurement and control of dosages of electrical energy applied to patients from short wave heat machines of the type adapted to use in physical therapy.

Broadly speaking, short wave physical therapy comprehends'the generation of heat in human tissues by means of electrical instrumentalities adapted to provide'energy to the issues in the form of rhythmic oscillating currents, which vary in direction of flow at highly frequent intervals. At the present time the short wave heat treatments are recognized to be of value in the treatment of infections in the respiratory tracts, in various suppurative processes, in chronic arthritis, in pneumonia and in the treatment of bursitis, and in similar instances'where heat is expected favorably to influence physical conditions. r

In general, two methods have been used in the past to induce short wave currents into the body or into the body parts which are afilicted.

The first of these is called the condenser method and involves the use of insulated spaced plates or pads. These plates or pads are associated with a short wave current generating apparatus, and, when a body of tissueis placed between these applicators, the current flows through the body by reason of its electrical capacity. During the passage (the body in a sense acts as a resistance) some of the electrical energy is converted or transformed into heat. This heat in other words is generated in situ. When plates are used, it is conventional to mount these adjustably to provide a convenient mannor for treatment, for example, of the head, knees, shoulders, ankles, etc., in instances where pressure or contact of pads is undesirable. Pads generally are placed on either side of and in contact with the particular body sector inten'led'to be treated.

The second method of applying short wave currents to the body is known as the induction method. This method is adapted particularly to use in fever therapy, and to the treatment of the internal parts of the body, or those parts which are very irregular in size and shape. In the induction method the heating isnot due primarily to currents passing through the body but rather to heating effects which are caused by the establishment and flow of secondary currents induced in the tissue being treated, by the current flowing in the applicator, which usually comprises a cable or coil wound around the aiflicted tissu'e.

While there has been a variety of difierent types of apparatus adapted to use for the production of short wave currents oscillating at highly frequent intervals, machines of the spark gap type, or of the electron tube type have been ,most widely accepted. In the first of these types, the short wave current is provided through spark interruptions in the flow of a given source current by means of a spark gap. In the other type, a short wave current is provided through current emissions from one or more triode electron tubes. The present invention is directed to improvements in the electron tube type of generating apparatus.

While the electrical circuits and various electrical instrumentalities adapted to produce short wave currents have been understood quite fully in the past, still, it is recognized quite generally .in the medical arts that the success of heat therapy in the treatment of ailments, where the technique is known to be of value, depends quite largely upon the skill and experience of the physical therapist or operator, as well as upon the regulated establishment of predetermined heat conditions.

Briefly, it is a primary objective of the present invention to provide controls in the heat machines by means of which at least some of the factors which, in their control, have depended so largely upon the skill and experience of the operator, are rendered less complex. and more easily controllable.

Broadlyspeaking, the degree of heat established, in a given mass of tissue in a patient by means of short wave currents applied to the body, either by the inductance method or by the condenser method is a function of the power or energy supplied to that body. In the actual practice of physical therapy, however, this broad generality is of little or no useful significance for the reason that the characteristics of the various masses of tissue are so variable and for the reason that, though time .01 treatment is controllable, still the amount of energy received by a given patient has not been subject to measurement accurately or in any practical manner. In the treatment of leg tissues, for example, the load which is imposed upon the generator is variable from patient ,to patient, even when there is no variation inthe relationship of the applicator elements to the leg. On the other hand, the load imposed during the treatment of the abdomen of a given patient is different from the load imposed when the shoulder for example is placed in a particular short wave circuit for heat treatment. And in either instance, the great difliculty has been that satisfactory measurement of the amount of energy received has not been possible.

The problem of measurement of energy by the part afflicted is complicated still further by reason of the fact that the load, during the treatment of any of these various parts of the body, varies in accordance with the relationship to the body parts, of the applicator elements from which the energy is provided. Thus, if pads be used, in contact with the parts, then the characteristics which influence the load upon the generator are not the same as the characteristics which influence the load when plates are used, or when a cord s wrapped around the mass of tissue in question. Likewise, the nature of the mass of tissue, its size, the regularity or irregularity of its shape and surface and the degree of adjacency of the applicator all comprise factors which affect the dosage received. And, of course, it is not possible to measure the result directly, even though the generation of a given degree of heat for a given period of time is the primary objective in heat therapy.

It is an object of the present invention to provide a control in the generating circuit of a phys ical therapy heat machine which is substantially directly indicative of the dosage of current to which a given patient undergoing treatment from the circuit is subjected. Otherwise expressed, it is the object of the invention to provide a meter for measuring the dosage of short wave energy applied to a patient, and to measure and control this amount of dosage.

A still further object of the invention, moreover, is to provide in a short wave current gen erating apparatus, control instrumentalities which enable the application of dosages of predetermined quantity to patients of different types and to the respective parts of the patient, substantially irrespective of the variations of the patient's circuit characteristics or of the variations in the relationships of the applicators to the parts undergoing treatment.--

Further objects, and the advantages of the accurate irrespective of the nature of the type of treatment or of the type of tissue being treated. Thirdly, the invention resides in the selection of instrumentalities from the electrical art, and the arrangement of these instrumentalitles to solve the problem of dosageof short wave energy in the wholly unrelated art of physical heat therapy.

Briefly, I have discovered that the linear subtractive combination, or difference between the plate current and the grid current in an electron tube type short wave diathermy machine is substantially proportional to the amount of energy received by, and thus, to the amount of heat generated in a patient or an object included as an element in the short wave circuit of the generator to receive energy therefrom or be heated thereby. Otherwise expressed, and more particularly from the point of view of heat therapy, the present invention is predicated upon the discovery and determination that the amount of heat generated or induced in a patient undergoing treatment is substantially proportional to the difference between the currents applied at the plates and grids of the electron tube elements in the generating circuit substantially irrespective of variations in the coupling of the patient in the short wave circuit.

By reason of these determinations it is the concept of the present invention differentially to measure plate current minus grid current in an electron tube short wave generating circuit. This differential or linear subtractive value preferably is plotted or indicated by a meter needle upon the scale of a meter in which the currents differentially are applied. Otherwise expressed, the grid circuit and the plate circuit are connected to the meter for opposition of the current in the grid circuit with the current in the plate circuit.

The meter preferably is adjusted to read no load at. zero diiierentialand to read full load at the maximum permissive differential. According to the present invention, therefore, the therapist measures and controls substantially directly the quantity of energy as well as the time of treatment. It is highly significant, of course, that thevariations in dosage which heretofore have been caused by variations in coupling'and .variations in the types of tissue being treated subpresent invention are disclosed in the following specification, and in the drawing in which:

Figure 1 shows the improvement of the present invention embodied in an electron tube circuit adapted to provide short wave currents appropriate to utilization through the condenser or inductance methods, as well as appropriate for use in electro-surgical sections.

Figure 2 illustrates diagrammatically a simplifled electron tube circuit in which the improvement of the present invention is embodied.

In the past, control of dosage has depended largely upon the skill of the operator. According to the present invention dosage of short wave energy is measured and controlled in accordance with a measurable electrical value in the gen.- crating circuit, which I have discovered more nearly to approximate the amount of energy actually received by a patient undergoing treatment in the patient's circuit than any of the modes of controlling or measuring diathermy,

dosage which heretofore have been used. The

invention resides first in the discovery of this relationship of factors by means of which dosage in the patient is measured, and secondly in the, I

determination that the value measured in the electrical circuit is a guide which is substantially stantially are obviated, and that a practical working dosage guide directly is provided to the therapist who heretofore has relied so completely on empirical controls and on experience alone.

In" the types of electron tube generators to which the present invention is directed it is necessary usually to indicate the voltage applied to the filaments of the tube generators to protect these tubes from being subjected to a voltage too high or too low for safe working conditions. Generally, the-filament voltage is metered directly through a meter display on the control panel ofthe machine. This metering and control of the voltage in the filaments of electron tubes in circuits of the type to which the invention relates is important in the practical electrical operation of the machine. In the first place, the voltage in the filaments controls the temperature at which the filaments operate. If the temperature is too high then the life of the tubes is very short; on the other hand, if the temperature is too low, then, particularly in the tubes of the thoriated filament type, the thorium atoms'or particles do not diffuse to the surface sufiiciently rapidly to provide proper electron emission. In other words if the electron emission is too low then difliculty is encountered in producing suflicient energy for proper oscillation. Metering of the filament voltage is useful particularly in starting the machine and in its practical operation.

In view of this consideration, a further object of the invention has been to control the voltage applied to the filament elements of electron tubes of the short wave generating apparatus during the periods of starting and of operation, (to insure safe electrical circuit conditions) as well as to control the dosage received by a patient coupled with this electrical circuit. It is a concept of the invention to measure filament voltage on a meter for machine control, and to measure the difference between plate and grid currents on this meter for dosage control. It is preferred that this meter be included in the circuit normally to indicate the value of the difiference between plate operation of the machine from the electrical point of view and a dosage meter for operation of the machine from the more important point of view of the patient.

In the accompanying drawing I have shown the improvements of the present invention embodied in an oscillating circuit which employs a pair of electron tubes. The particular type of circuit which is shown in the drawing at Fig ure 1 has been found to be well suited to use in electro-therapeutic machines. It will be understood, however, that the invention is not limited to this particular type of circuit which is disclosed. The improvements are adapted general ly to use in the more simplified types of circuits, such as the one shown in Figure 2, as well as to circuits of a more complex nature.

The circuit shown in Figure l employs a pair of vacuum tubes W of the type having heating filaments H, plate elements l2 and grid elements l3. The filaments II are connected in parallel relation through leads Id, Id, which respectively are supplied with energy Er through leads l5, l5 taken from a secondary winding it of a transformer indicated generally at ll. Primary winding l8 of the transformer is supplied with energy through input terminals 09-49 which, during the operation of the machine, are

connected to a suitable alternatingcurrent source through main control switch 20.

The plates l2 of the electron tubes are mounted in parallel relation to receive current from a second secondary winding 2! of the transformer ll. One end of the transformer secondary winding 2| is connected through a lead 22 to one of the plates I2 and another lead 23 is taken from the lead 22 to the other plate element l2. Both the leads 22 and 23 respectively include impedance elements 24, 24.

The plates I2 are connected respectively through conductors 25-25 to the oppositeends of an inductance coil 26 having a center tap 21 which normally is in circuit connection with the remaining terminal of secondary 2| through a switch and meter circuit that is referred to in detail at a later point in the specification. The conductors 2525 respectively include appropriate pairs of condensers 28-88 and a condenser 29 is shunted across the opposite terminals of the inductance 26 to facilitate proper oscillation.

The grid elements l3 of the electron tubes H) are cross connected through leads 303il to taps 3l-3l located on opposite sides of the center tap 21 of the inductance 25. The cross connections 30 each respectively include condensers 32-42 and resistances 83-33 shunted around the condensers.

A variable output coil 34 inductively is coupled to the inductance coil 2t, with the terminals of the coil respectively connected through leads 35, 35, to out-put terminals or posts 36 and 31. Output terminals 38, 38 also are provided through taps 39, 39- respectively connected to the inductance or tank coil 25 on opposite sides of center tap 21.

A type of current (other than diathermy current) which the circuit of Figure 1 is adapted to provide is a surgical or cutting current possessed of dehydrating properties found through experience to be suit ablefor providing hemostasis under normal condition in operations of the general type for which electro surgery has been found to be particularly efllcacious. This circuit likewise provides coagulating current adapted to stop the flow of blood when a particularly vascular tissue is dissected or when blood vessels or small arteries are encountered.

Now, to accommodate usage of the circuit of Figure 1 for surgical cutting and coagulating, as well as for diathermy, an output terminal 40 is provided on a lead M, connected to terminal 36, and including a condenser 62. The electrosurgical scalpel is plugged in at the terminal 36 and. the patient is grounded to the terminal 31, which acts as the indifferent electrode terminal, or when current for coagulating vascular tissue is desired the scalpel is connected to terminal all, and the indifferent electrode likewise is connected to terminal 31.

For the various diathermy operations, the machine is used as follows:

When the induction method of heat treatment is desired a cord is connected across the terminals 38. This cord usually comprises a metallic conductor sufliciently flexible to be wound aroundthe aillicted body parts intended to be. treated. When the pad method of treatment is desired, the terminal of one of the pads is connected to the terminal 36 and the terminal of the other pad is connected to the terminal 31. The pads are placed on opposite sides of the particular body section for treatment.

When the plate method of treatment is demechanically are mounted on arms made adjustable to facilitate arrangement of the plates on opposite sides of, and adjacent to the body section undergoing treatment.

A'lead 44, which includes a pair of condensers 45, and a resistance 46, is positioned to connect the terminal 31 with a center tap M on the secondary element I6 of the transformer through a switch 48 indicated by the arrow).

Switch 48 controls circuit connection of the transformer center tap 41 to the terminal 31. The switch is adjusted so that the lead 44 is connected to the terminal 3! when the circuit is to be. used for electro-surgical purposes. To prevent the application of high voltage to the 4 plate and grid circuit currents.

patient in the event of short circuiting in the main generating circuit at a time that a patient is being treated, condensers 45-45 are connected in lead 44. The connection or lead 40 to the indifferent electrode terminal 31 maintains this terminal at low ratio frequency potential to prevent the operator from being-burned in the event that he should touch the patient during the course of operation. But, when the circuit is being used for the generation of heat in heat therapy the lead is disconnected from the terminal 31 through switch 46.

In the practice 01 the present invention, a meter 49 is utilized to indicate the grid-plate current differential. This meter preferably is a relatively sensitive meter of the type in which an armature or vane revolves in accordance with the magnitude of the current or the voltage applied to field coils disposed on either side of the armature.v Briefly, the meter 49 is connected in the electron tube circuit to measure the difl'erential of the plate current and the grid current. More specifically, it is the concept to provide connections to the meter from the respective plates and grid' connections in the circuit so that the grid current tending to flow in the meter is opposed by the plate current tending therein to flow. Otherwise stated, the meter is connected so that it will deflect according to the extent that the current in the plate circuit exceeds in value the current in the grid circuit.

By reason of the discovery that this difference closely approximates the quantity of energy received by a particular patient in the output circuit of the generator, the needle deflections therefore provide the guide by means of which diathermy or short wave dosage to a patient either is adjusted or controlled The preferred embodiment of the present invention is embodied in the circuit of Figure l as follows: i

A double pole, double throw switch preferably of the push button variety, as indicated gen-' erally at 50, is provided, with movable elements 5|, 5| of the switch connected to terminals 52, 52 respectively of the meter 49. This switch 50 preferably is adjusted so that the movable contacts 5|, 5|, normally contact stationary contact elements 53--53 which are in circuit con-' nection with the electron tube circuit so that a the meter normally readsthe differential of the More specifically, in the circuit shown, one of the contacts 53 is connected through a lead 54 to the B- terminal leading from the transformer secondary 2| (through the switchand meter, to the center tap 21). This lead is designated 1 or the plate 7' current" lead. The other contact element 53 is connected through a lead 55 to complete circuit connection from the terminal of the secondary 2| to-the center tap 21. From lead which is designated 1;, or grid current" lead, connections 56, 56 are taken respectively to the filament connectors I4. l4, through filament bypass condensers 51, 51, one for each lead 55.

(The filament by-pass condensers do notrelate particularly to the present invention of dia-'- thermy dosage control, but are used to facilitate general short wave circuit operation.) .The lead 54 places the meter 49 in partial circuit connection for measurement of the plate current, and the lead 55 places the meter 49 in partial circuit connection with the grid current.

To complete the grid and plate circuit conmovable contact elementj8l, 8| of the switch 10.

-minals 54 and 55. This resistance is made variable in order to adjust the meter 49 to exhibit zero deflection when no load is on the generating circuit and to exhibit full scale deflection when full load, or the maximum permissive load, is on the generator By moving the variable resistance contact element either to the right'or to the left more resistance is thrown in the plate, or the grid circuit connectors respectively to the meter, and, in this manner the subtractive combination of plate and grid currents is adjusted sothat the meter reads zero or substantially zero at no load.

Contact elements 6||6|l of the double pole, double throw switch 50 are placed respectively on sides of the movable elements 53-53 opposite to the sides on which the plate In and grid Ig contact elements respectively are disposed. The elements 60-450 are disposed for contact with the connect the contact elements 60, 6|] with the terminalsof the secondary winding l6 of the transformer l1. Lead 62 may include a resistance 64, to adjust the filament voltage E1 to a value suitable for'meter reading. A condenser 65 is shunted across the terminals of the meter 49.

When the push button switch is in the normal position (as with the actuator 6| distended) then the meter 49 reads the amount of energy being provided to a patient in the output circuit of the generator, through connection of the movable contacts 53, 53 and the plate and grid contact elements 54, Ip and 55, lg. The meter under these circumstances acts during the course of treatment as a guide to the dosage being received by a patient, in that the meter needle deflects in accordance with the difference by which the plate current exceeds the grid current. On the other hand, when the push button actuator 6| is depressed, then the meter 42 reads filament voltage Er and in this respect the value indicated by the meter is utilized particularly to adjust the machine to optimum operative, or oscillating conditions. Likewise this indication guides the operator and safeguards against the application of too great a voltage to the tube filaments. Y

In the circuit shown in Figure 2 a single electron tube is used. The plate element 65 of the tube is connected through a lead 51 to one end of an inductance coil 65, the other end of which is connected through a "B" battery to a pla contact 59 of a double pole, double throw switch indicated generally at 10. A radio frequency by-pass condenser 1| is shunted around the "3 battery, for safety purposes. Grid element 12 of the electron tube is connected througha lead 13 to one end of a second inductance coil 14, the lead 13 including a resistance 15 and condenser 15 in parallel connection with one another. The other end of inductance coil 14 is,connected through a lead 11 to grid contact 16 of the double pole, double throw switch 10. A radio frequency by-pass condenser 19 likewise is shunted across leads 11 and 51 for safety purposes. Meter 8|! is connected, as in. the manner shown in Figure 1, preferablyto A variable resistance82 likewise as in the manner shown in Figure 1, is shunted across the connector to't'ne plate contact 89 and the connector to the grid contact 18 and a filament return connection 83 to the variable resistance 82 in turn is connected to one of the terminals 84 oi the filament of the electron tube 65.' A lead 85 connects one terminal of the filament with filament switch contact 88, througha voltage control resistance 81. The other filament conv tact 88 is-connected respectively to the filament return oonnector'83. i,

In the circuit shown in Figure 2 the meter 80 is shunted across the movable contactors 8l8i of 4 switch 18. The meterfunctions in substantially the same manner as the meter shown in Figure 1. c When the switch isthrown so that'the meter is in connection with contacts 69 and 18, then the meter reads the subtractive combination of I1) and 13. On the other hand, when switch 10 is thrown for connection of meter 80 acrossterminals 86 and 88 the meter reads voltage Er im-- pressed on the filament of the electron .tube.

-The control of diathermy-dosage in the past has been particularly dimcult because of the complexity, and because of the variety of the factors I which influence the'amount of energy received by a patient undergoing treatment. By reason of the simple controls of the present invention which are predicated upomthediscovery of the peculiar relationship of the grid and plate circuit current values and the patients energy, the empirical guides upon which the diatherapists heretofore have relied largely are obviated. In the present improvements. twocontrols, one protecting the cate the difierence between the current in' the grid circuit and the current of the plate circuit, whereby the meteris actuated to indicate power output or the therapeutic apparatus, and means in circuit connectionpwith the meter for adjusting the meter to read zero deflection at no load and to deflect to a maximum degree when the oscillating circuit, is operated at maximum. permissive load. r 2. In an electro-therapeutic apparatus for dia ,thermy treatments, a circuit generating oscillating diathermic currents, including anelectron tube having a grid element and a plate element, agrid circuit including the grid element of the tube and a plate circuit including the plate element 'of thetube, means for indicating the power output of the apparatus to a patient being treated, comprising, a meter, circuit connections from the grid circuit and the plate circuit to the meter.

2 0afor effecting opposition of the current of thergrid circuit'to the current of the plate circuit, where by the meter is actuated to respond to the differ ence between the plate and grid currents to indicate poweroutput of the therapeutic apparatus to a patient being treated.

'3. In an electro-therapeutic generatingapparatus for producing diathermic oscillating currents comprising, a circuit including an electron patient and the other the machine, cooperate,

through simple circuit instrumentalities, which arelow in cost and sturdy and reliable in operation.

Having described my invention, I claim: 1. An electro-therapeutic apparatus for diathermy treatments, means for indicating power output of the apparatus to a patient being treated, comprising, an oscillating circuit having an electron tube, the tube having grid and plate elements, a grid circuit including the grid element of the tube, a plate circuit including the plate element of the tube, a meter in circuit connection with the grid circuit and-the plate circuit to indi- 4 /the therapeutic apparatus and .a variable resistance in circuit connection with the meter for adjustment oi the meter deflection to zero' 'reading at no load and maximum deflection at maximum permissive load upon the diathermic current generating apparatus. I

CARL mcmnmeen. 

